The overall goal of the proposed research is the development of novel polymerized and unpolymerized vesicle systems for targeted drug delivery in cancer treatment. These systems will be based on cleavable surfactants. A surfactant is cleavable if it contains a linkage separating its hydrophilic and lipophilic portions that is stable under some conditions but labile under others. Cleavage at the linkage converts the surfactant into non-surfactant compounds, and it would therefore result in rupture of a cleavable surfactantbased vesicle with concomitant release of an entrapped compound. Both pH and UVsensitive linkages will be employed. The former will allow targeting to tumors, which can have lower pH's than normal tissue. The exact nature of the linkage and the polymerized/unpolymerized character will be varied to give a series of targeted vesicles with a wide spectrum of release kinetics that would otherwise be difficult if not impossible to obtain. Detailed goals are as follows: (1) the preparation of doublechain, cleavable surfactants and polymerized analogues; (2) the characterization of polymerized and unpolymerized vesicles formulated from them; (3) the demonstration that such vesicles have potential for drug delivery in cancer treatment.